Cleaning composition and method



ing the tin.

United States 2,836,566 CLEANING CQWOSITION AND METHOD Ira J. Duncan, Detroit, Mich., assignor to Detrex Chemil v cal Industries, Inc., a corporation of Michigan No Drawing. Application January 27, 1954 Serial No. 406,595

3 Claims. (Cl. 252-137) This invention relates to a composition and a method of cleaning metal objects, and more particularly concerns atent damage to the tin surface has long presented a problem.

Such pans are usually cleaned in hot solutions of alkaline cleaners consisting of alkali metal salts of silicates, phosphates, carbonates, borates, etc.-, together with suitable t-in inhibitors; Well known inhibitors are the alkali metal salts of chromates, dichromates and silicates. Even with these inhibitors, complete protection to the tin surface is not always possible, especially at a pH above about 12. Cleaners of a pH below about 12 have less tendency to attack the tin surface, but their cleaning is usually slow which makes it necessary to boil the pans for many hours to eifect cleaning.

Some pans used in the bread baking industy are made oftin coated steel and have reinforcing bands constructed Recently,

while the straps may have tin, tin oxide, aluminum, or

aluminum oxide surfaces. Bread pans constructed of both tin plated steel and aluminized steel bands present an even more diflicult cleaning problem, since the presence of these unlike metals causes an increased tendency .for galvanic cell activity to occur, which results in severe tin attack. i. p t

\When two diiierent--metals are brought into contact with the cleaningsolution an electro-chemical phenomenon is involved. In the case of tin coated steel pans bearing an oxide film and covered with carbonized grease and other bakery soils, there is a reducing action on the oxide coating. Thereby, numerous small areas of the oxide fil m are often removed which exposes the pure metalto the solution at these points, Themore noble metal oxide and the pure metal in contact with the cleaning solution tend to set up agalvanic cell action. Also, when two metals, e. g., tin and aluminum, are in contact with a common cleaning solution there is a tendency for both tin and alumium to 'go into solution. When this takes place the metals become electro-negative. Since the solution potential of tin and aluminum are not of the same magnitude there is set up a galvanic action between 2 the two metals. Pans constructed of both tin and aluminum and covered with bakery soil might exhibit an even greater galvanic action than similar clean pans.

The function of silicate or chromate inhibitors is to passivate the metal surface and thus prevent the oxide from being removed and to prevent the galvanic cell activity. This is sometimes diflicult to accomplish completely with certain types of bakery soil and with certain types of pans. Galvanic cell activity as outlinedabove interferes with the inhibiting action of chromate or silicate inhibitors.

It is accordingly an object of this invention to provide a composition and method which overcome the foregoing difiiculties and disadvantages. Another object is to provide a method of cleaning carbonizedand grease-carbon incrustations from baking containers having surfaces containing at least two materials selected from the group have discovered a new inhibitor for use in alkaline cleaners which prevents attack on the tin surface even at a pH of 12 or higher. The inhibited composition consists of an alkaline solution containing the copper-amine complex ion.

The copper-amine complexion may be made by combining a water soluble copper salt with an organic amino compound. A wide variety of water soluble copper salts are suitable for the practice of this invention, including cupric sulfate, cupric chloride, cupric acetate, cuprous chloride and cuprous cyanide. There is also a wide selection of monoor poly-amino organic-compounds which coact with the copper ion in accordance with this inven tion, including 1,3-diamino butane; monet-hanolamine, 2-

amino, Z-methyl, propanol-l; PolyamineT (distillation,

residues from the distillation of amines," sold by Carbide and Carbon Chemical Corp, New York); CSC38 (distillation residues from the distillation of hydroxy amines, sold by Commercial Solvents Corp., Terre Haute, Indiana). Also, several synthetic detergents of the amino condensation type were shown to be effective. Examples of the latter are the Ninols manufactured by the Ninol Laboratories of Chicago, 111., which are amides formed by the reaction between fatty acids and alkanol amines. V

The above list of hopper salts and organic amino compounds is merely illustrative of the types of compounds which protect tin pans in alkaline solutions, and is not intended to be exhaustive. Any compatible combination of copper salt and organic amino compound may be utilized provided the copper salt is water soluble producing a copper ion which reacts with the amine, and provided the amino compound includes a water-soluble amino (NH group. Soluble compounds, such as N'H OH, are not suitable.

If desired, the inhibit-or may be mixed as a copperamino complex. However equally good results are obtained by mixing together the alkaline components, the coppersalt and the amino compound. The latter method is more convenient from the manufacturing standpoint. It is emphasized that the presence of both the copper ion and the amino compound is necessary in order to protect the metal surface in accordance with this invention.

The preferred range of proportions for a mixture of solid ingredients is about -93% by weight strong alkali cleaning chemicals such as alkali metal silicates,

carbonates, phosphates, borates, hydroxides and the like, about 210% by weight water soluble copper salt and about 515% by Weight organic amino compound. In solution, the copper amine complex ion is formed, and this should be present in a proportion of approximately 315% by weight based on the total weight of copper amine and complex plus alkali cleaning chemicals, the weight of the complex being calculated on an additive Cu and amino group (NH basis.

Typical cleaning compositions containing copper salts and amines which effectively clean tin-aluminum pans in a common solution without attack to the metal surfaces appear below.

Percent Sodium metasilicate 2050 Trisodium phosphate -25 Soluble copper salt 3-10 Amino compound 4-15 Soda ash 0-63 The above ranges of percentage composition are preferred ranges, but are not to be taken as setting out the limits of eflectiveness of this invention.

The following specific examples further illustrate preferred compositions and methods in accordance with this invention:

Example 1 A composition was prepared consisting of: I

Pounds Sodium metasilicate 50 Sodium carbonate 35 Polyamine T (amino acid distillation residue) 10 Cupric chloride The above composition was dissolved in water at a concentration of 4.5 ounces per gallon. Strips of burned-in tin were immersed in the solution at boiling temperature for several hours and, upon removing the strips, it was observed that the tin was not visibly attacked.

It has been disclosed in U. S. Patent No. 2,050,122 to W. Reuss et al. that the cobaltic amine ion is an effective corrosion-preventing agent for tin when added to certain alkaline cleaning compositions. However, when this agent was tested in cleaning compositions for cleaning combination tin and aluminum bread pans protection was not obtained, resulting in severe attack on the tin surface.

Example 2 A composition was prepared consisting of:

Pounds Sodium metasilicate 50 Sodium carbonate 35 Polyamine T (amino acid distillation residue) 1O Cobaltic chloride 5 The above composition was dissolved in water at a concentration of 4.5 ounches per gallon. Strips of burnedin tin were brightened within 15 minutes when placed in the solution at boiling temperature.

Example 3 The procedure of Example 1 was repeated, substituting equal amounts of cupric sulfate and cupric acetate for copper chloride, and in each instance substantially identical results were observed.

Example 4 A mixture was prepared consisting, by weight, of:

Percent Sodium metasilicate 48 Sodium chromate Soda ash 30 Cupric sulfate 2 Polyamine T 10 This mixture, dissolved as in Example 1, was efifective for cleaning baked-in tin pans having aluminized steel bands, and did not visibly corrode the tin or aluminized steel even after immersion for three hours.

Example 5 Another mixture, specified below, was tested as in Example 4, with substantially identical results:

Percent Sodium metasilicate 35 Sodium chromate l0 Cupric sulfate 2 Polyamine T 8 Sodium bicarbonate 20 Soda ash 25 Example 6 Sodium metasilic ate 50 Soda ash 38 Cupric sulfate 5 Mixed amino hydroxy compounds (amino acid distillation residue supplied by Commercial Solvents Corp.) 7

Example 7 Sodium metasilicate 5O Soda ash 39 Cupric sulfate 5 Mixed amino hydroxy compounds (amino acid distillation residue supplied by Commercial Solvents Corp.) 6

Example 8 SOCllUlTl metasilicate 25 Tri sodium phosphate 25 Soda ash 39 Copper sulfate 5 Mixed amino hydroxy compound 6 Example 9 Sodium metasilicate 5O Soda ash 35 Polyamine T 10 Cupric chloride 5 Burned-in tin strips, placed in a boiling solution of each of these mixtures at 4 to 5 ounces per gallon, Were not attacked after several hours. With similar procedure, the same results were obtained in Examples 10-13.

The above chemicals were dissolved in water in an amount to produce a concentration of 4 to 5 ounces per gallon. At boiling temperature, even after several hours ciably attacking any of said tin, aluminum or oxides, in

immersion, burned-in tin strips were not substantially attacked. 1 p The same procedure was followed, producing the same results, substituting the mixtures of Examples 15-17 which follow:

Example 15 Percent Sodium metasilicate 50 Soda ash 39 Copper sulfate r 5 Monoethanolamine 6 Example 16 Sodium metasilicate -2 Q. 50 Soda ash m.-. 39 Copper sulfate p 5 Z-amino Z-methyl l-propanol 6 Example 17 Sodium metasilicate 50 Soda ash i 39 Copper sulfate 5 Ninol amino condensate product (mixed fatty acid alkanol-amine) 6 Example 18 v 1 t r t Pounds Soda ash 75 Triethanolamine 15 Cuprous sulfate p 10 Example 19 Soda ash Trisodium phosphate 20 Z-amino Z-methyl l-propanol -2... 15 Cupric acetate 10 1 Example 20 Sodium tetraborate 20 Soda ash 75. Monoethanolamine 10 Cuprous chloride p 5 Having thusdescribed my invention, I claim: 1. In a method of removing bakery deposits from a work object having a surface selectedfrom the group which includes tin and aluminum and their oxides without apprewhich method said object is immersed in a strong but aqueous alkali cleaner solution having a pH above about 11.8 in the presence of a dissimilar surface selected from the group consisting of tin, aluminum and their oxides, which solution tends to attack the surface of said work object by galvanic corrosive action, the novel step which comprises immersing said work object in a solution consisting essentially of water and about four to five ounces per gallon of a solute consisting essentially of about 20-5 0% by weight alkali metal metasilicate, 3-10% water-soluble copper salt selected from the group consisting of sulfate, chloride, acetate and cyanide, and about 4-15% .by weight amine selected from the group consisting of 1,3-diamino butane, monoethanolamine, 2- amino-Z-methyl l-propanol and tri-ethanolamine, and about 25-63% by weight soda ash.

2. An alkaline cleaning solution for removing bakery incrustations from baking containers, said solution having a pH above about 11.8 and consisting essentially of water and about 4 to five ounces per gallon of solute consisting essentially of about 20-50% by weight alkali metal metasilicate, 3-10% water-soluble copper salt selected from the group consisting of sulfate, chloride, acetate, and cyanide and, about 415% by weight amine selected from the group consisting of 1,3-diamino butane, monoethanolamine, 2-amino-2-methyl l-propanol and thiethanolamine, and about 25-63% by weight soda ash, the percentages being based upon the total weight of said alkali metal metasilicate, soda ash, copper salt, and amine.

3. An alkaline metal cleaning composition for removing bakery incrustations from bakery containers consisting essentially by weight of about 50% sodium metasilicate, 39% soda ash, 5% copper sulfate, and 6% monoethanolamine.

References Cited in the file of this patent UNITED STATES PATENTS 2,050,122 Reuss et a1. Aug. 4, 1936 2,168,909 Mason Aug. 8, 1939 2,377,966 Reed June 12, 1945 2,525,079 Reeder et al. Oct. 10, 1950 2,706,180 Sylvester Apr. 12, 1955 2,731,420 Sylvester Jan. 17, 1956 FOREIGN PATENTS 661,370 Great Britain Nov.'21, 1951 OTHER REFERENCES Sequestrene, pp. 5, 9, 27, pub. by Geigy Industrial Chemicals, New York (1952).

Synthetic Detergents by McCutcheon, p. 405, pub. by MacNair Dorland, New York (1950).

May 1958 6. MR. REURE E-rm. 2,336,567

' APPARATUS FOR GENERATING'SMQKE, FOG, AEROSOL-S AND LAYERS 0F GAS 0R DISPERSIQNS Filed Jln' e, 1953 a Sheets-Sheet 1 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,836,566 May 27, 1958 Ira J, Duncan Column 1, line 39, for "industy" read industry line 69, for "alumium" read alumin column 2, line 52, for "hopper read m copper column 3, line '7, strike out hand"; line} 57, for "ounches" read ounces column. 6, line 27, for "thiethanolamine" read tri=ethanolamine Signed and sealed this 21st day of October 1958,

SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Oficer Commissioner of Patents 

3. AN ALKALINE METAL CLEANING COMPOSITION FOR REMOVING BAKERY INCRUSTATIONS FROM BAKERY CONTAINERS CONSISTING ESSENTIALLY BY WEIGHT OF ABOUT 50% SODIUM METASILICATE, 39% SODA ASH, 5% COPPER SULFATE, AND 6% MONOETHANOLAMINE. 